Most of the photopatterning materials based on epoxy resins are utilizing photoacid generators (PAGs) which generate superacids as catalysts. They have been used for high aspect ratio photoresists in the fabrication of MEMS devices. However, there is a drawback that the acidic species from PAGs will induce metal corrosion. One of the approach to overcome this problem is the use of photobase generators (PBGs) because organic bases would induce no corrosion. Although there is a large number of investigation of PBGs in past time, only few articles have mentioned photoreactive materials relying on PBGs due to its low photosensitivity. We report here highly sensitive photopatterning materials comprising PBG and an epoxy resin bearing carboxylic acid groups. As a result, the photopatterning material showed higher photosensitivity when compared to conventional epoxy resin systems. We obtained high photosensitivity (up to 900 mJ/cm 2 ), high resolution (10 m line and space) patterning materials in thin films of 10 m in thickness.
Most of the photopatterning materials based on epoxy resins utilize photoacid generators (PAGs), which generate superacids as catalysts. They have been used for high aspect ratio photoresists in the fabrication of MEMS devices. However, there is a drawback, in that the acidic species from PAGs will induce metal corrosion. One of the approaches to overcome this problem is the use of photobase generators (PBGs) because organic bases would induce no corrosion. Although there have been many previous investigations of PBGs, only a few articles have mentioned photoreactive materials relying on PBGs because of their low photosensitivity. We report here highly sensitive photopatterning materials comprising PBGs and an epoxy resin bearing carboxylic acid groups. As a result, the photopatterning materials showed higher photosensitivity than conventional epoxy resin systems. We obtained highphotosensitivity (up to 900 mJ/cm 2 ), high-resolution (10-μm line-and-space) patterning materials in films, 10 μm in thickness.
Most of the photosensitive materials are based on photoradical and/or photocationic polymerization, because many photoradical and photoacid generators, monomers, and oligomers are commercially available. Although photosensitive materials based on basecatalyzed reactions have merit in preventing erosion of metallic substrates, Photobase generators (PBGs) generally have lower quantum yields when compared to photoradical initiators (PIs) and photoacid generators (PAGs). We report here novel PBGs based on a benzoin structure. This PBG can liberate radicals as well as bases with high efficiency by iline irradiation, so that a homogeneous organic-inorganic hybrid film can be formed. As a result, the hardcoating materials based on the organic-inorganic hybrid show high pencilhardness (4H), transparency, and scratch resistance compared to coating materials using conventional PIs and PBGs.
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